Antagonistic Inhibitory Circuits Integrate Visual and Gravitactic Behaviors.

Larvae of the tunicate Ciona intestinalis possess a central nervous system of 177 neurons. This simplicity has facilitated the generation of a complete synaptic connectome. As chordates and the closest relatives of vertebrates, tunicates promise insight into the organization and evolution of vertebrate nervous systems. Ciona larvae have several sensory systems, including the ocellus and otolith, which are sensitive to light and gravity, respectively. Here, we describe circuitry by which these two are integrated into a complex behavior: the rapid reorientation of the body followed by upward swimming in response to dimming. Significantly, the gravity response causes an orienting behavior consisting of curved swims in downward-facing larvae but only when triggered by dimming. In contrast, the majority of larvae facing upward do not respond to dimming with orientation swims-but instead swim directly upward. Under constant light conditions, the gravity circuit appears to be inoperable, and both upward and downward swims were observed. Using connectomic and neurotransmitter data, we propose a circuit model that can account for these behaviors. The otolith consists of a statocyst cell and projecting excitatory sensory neurons (antenna cells). Postsynaptic to the antenna cells are a group of inhibitory primary interneurons, the antenna relay neurons (antRNs), which then project asymmetrically to the right and left motor units, thereby mediating curved orientation swims. Also projecting to the antRNs are inhibitory photoreceptor relay interneurons. These interneurons appear to antagonize the otolith circuit until they themselves are inhibited by photoreceptors in response to dimming, thus providing a triggering circuit.

Baseline Visual Acuity at Wet AMD Diagnosis Predicts Long-Term Vision Outcomes: An Analysis of the IRIS Registry.

BACKGROUND AND OBJECTIVE: Clinical trials in neovascular age-related macular degeneration (nAMD) demonstrate that high visual acuity (VA) can be maintained, and low VA can be improved with anti-vascular endothelial growth factor (VEGF) treatment. Few real-world data investigating the relationship between baseline VA and long-term outcomes exist. This study compares VA at diagnosis and after treatment using data from a large patient registry. PATIENTS AND METHODS: Retrospective study of IRIS Registry patients diagnosed with nAMD in one or both eyes between January 2013 and June 2017. Patients received at least two anti-VEGF injections in the study eye(s) less than 45 days apart during the study period. Primary outcomes were the percentage of eyes with 20/40 VA or better at diagnosis and association of VA at diagnosis with longer-term visual outcomes. RESULTS: The study included 162,902 eyes. Among all included eyes, 34.3% presented with 20/40 VA or better at diagnosis. Patients with 20/40 vision or better at baseline maintained a mean VA of 20/40 or better for 2 years after treatment initiation. CONCLUSIONS: Baseline VA at nAMD diagnosis predicts long-term VA outcomes. Early diagnosis before VA is adversely affected is a key factor in preserving vision in patients with nAMD. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:633-639.].